Fixed wireless networks transmit data point-to-point through the air over a terrestrial microwave platform rather than through copper or optical fiber and typically use a directional radio antenna on each end of a wireless link. These antennas are designed for outside use and to accommodate various weather conditions, distances and bandwidths. The antennas are usually selected to make the beam as narrow as possible and thus focus transmit power to their destination, increasing reliability and reducing the chance of eavesdropping or data injection. The links are usually arranged as a point-to-point setup to permit the use of these antennas. The point-to-point setup also permits the link to have better capacity and/or better reach for the same amount of power. Unlike wired networks, the quality of service and capacity between two points on a wireless network may fluctuate due to weather conditions or background transmissions. Millimeter waves suffer specifically from signal absorption due to fog or rain and, millimeter waves in the 60 GHz range suffer from the effects of oxygen absorption as well.